Professor Daniell observes, that “by means of this magneto electrical machine, all the well known effects of Voltaic currents may be very commodiously produced. When the communication is made between the spindle and the revolving disc, by means of a fine platinum wire, instead of the dipping points, the wire may be maintained at a red heat; although the effect being produced by alternating currents in opposite directions, a kind of pulsation, or intermission of the light, may be discerned. Upon making the communication between the two mercury cups, by means of copper cylinders _grasped_ in the _hands_, a continued painful contraction of the muscles of the arm takes place, which destroys voluntary motion, and, under certain circumstances, is perfectly _intolerable_.
“The general expression of these phenomena may be thus stated: whenever a piece of metal is passed, either before a single pole, or between the opposite poles of a magnet, or before electro magnetic poles, whether ferruginous or not, so as to cut the magnetic curves, (or lines, which would be marked out by a spontaneous arrangement of iron filings,) electrical currents are produced across the metal, transverse to the direction of motion.”
This important instrument also depends, for its action, upon the principle discovered by Dr. Faraday, that electricity was developed in conducting bodies, when they were moved in a certain direction, in the neighbourhood of permanent magnets. Since the beautiful and ingenious invention which Mr. Saxton was the first to make, no valuable improvements have been made in this machine, except those introduced by Professor Page.
The first important change in the machine, was the adaptation of his pole changer to the machine, in place of the break pieces, which were used in all the modifications up to that time; and another equally useful improvement, consisted in the arrangement of the permanent magnets and armatures. Previous to this last improvement, these machines were constructed with a single permanent magnet, and one or more revolving armatures, necessarily involving great disadvantages. Page’s improvements were completed in February, 1838, and shortly after published in Silliman’s Journal. He was also the first to suggest the combination of several machines under one mechanical movement, as the best mode of augmenting power in this way.